OOP - new Class inside a Class

Hello.

I trying to create a new class instance inside of a existing class. For example:

I got a class for the whole map, and a class for the tiles, like grass, water, wall, etc…

Creating the array of the whole map, each value was suppose to be a new class of the tiles, something like this:

map[new_name] = new tiles(array*[j]);

But this doesnt seems to work very well. I got this error:

**Error** D:\map.as: Line 42: There is no method with the name 'tiles'.
     				map[new_name] = new tiles(array*[j]);

Total ActionScript Errors: 1 	 Reported Errors: 1

Thanks in advance